Field of the Invention
Embodiments of the invention relate to a solar cell module having an interconnector electrically connecting a plurality of solar cells to one another and a method of fabricating the solar cell module.
Description of the Related Art
Recently, as existing energy sources such as petroleum and coal are expected to be depleted, interests in alternative energy sources for replacing the existing energy sources are increasing. Among the alternative energy sources, solar cells generating electric energy from solar energy have been particularly spotlighted.
A conventional solar cell includes a substrate and an emitter layer, each of which is formed of a semiconductor, and electrodes respectively formed on the substrate and the emitter layer. The semiconductors forming the substrate and the emitter layer have different conductive types, such as a p-type and an n-type. A p-n junction is formed at an interface between the substrate and the emitter layer.
If light is incident on the solar cell, electrons inside the semiconductor become free electrons (hereinafter referred to as “electrons”) by the photoelectric effect. Further, electrons and holes respectively move to an n-type semiconductor (e.g., the emitter layer) and a p-type semiconductor (e.g., the substrate) according to the p-n junction principle. Then, the electrons and the holes are respectively collected by the respective electrodes electrically connected to the emitter layer and the substrate.
At least one current collector, such as a bus bar, is formed on each of the emitter layer and the substrate. The at least one current collector on the emitter layer is electrically connected to the electrode of the emitter layer, and the at least one current collector on the substrate is electrically connected to the electrode of the substrate.
Because a very small amount of voltage and current are generated from one solar cell having the above-described structure, a solar cell module fabricated by connecting in series or parallel several solar cells to one another is used to obtain a desired output. The solar cell module is a moisture-proof module fabricated in a panel form.
In the solar cell module, the electrons and the holes collected by the current collectors of each of the solar cells are collected by a junction box formed in the rear of the solar cell module, and an interconnector is used to connect the several solar cells to one another.
The interconnector is attached to the current collectors of the several solar cells using infrared rays, a heated gas, a local heating material, a laser, etc., so as to electrically connect the bus bars to one another.
However, the size of a light receiving surface of each of the solar cells of the solar cell module is reduced because of the interconnector. More specifically, because the size of the light receiving surface of the solar cell is reduced by the size occupied by the interconnector, a photoelectric transformation efficiency of the solar cell module is reduced.
Recently, the solar cells are electrically connected to one another using an interconnector having an uneven surface so as to minimize such a problem. In the solar cell module using the interconnector having the uneven surface, a portion (for example, light incident on the uneven surface of the interconnector) of light incident on the light receiving surface of the solar cell is reflected from the uneven surface of the interconnector and then is again incident on the light receiving surface of the solar cell due to light scattering.
In other words, the interconnector having the uneven surface improves the photoelectric transformation efficiency of the solar cell module to increase an output of the solar cell module. However, a process for forming the uneven surface of the interconnector has to be added. Accordingly, the manufacturing cost of the interconnector increases.
Further, because the interconnector is transferred, stored, and used in a state where the interconnector is wound on a spool, a foreign material may be attached to an uneven space between the uneven surface and an even surface (i.e., a planarization surface) of the interconnector. If the planarization surface presses the uneven surface, the uneven surface is deformed. Thus, the light scattering due to the uneven surface is reduced.
Further, because the uneven surface is formed entirely on one surface of a ribbon, when the adjacent solar cells are electrically connected to one another using the ribbon, an attachment strength between the ribbon and a back surface of the substrate of each of the adjacent solar cells is reduced in an attachment portion between the ribbon and a current collector positioned on the back surface of the substrate of each of the adjacent solar cells. Thus, a separate adhesive has to be used so as to prevent a reduction in the attachment strength resulting from the uneven surface of the ribbon.